1. Field of the Invention
The present invention relates to an image forming apparatus which jets a liquid droplet onto a recording medium (medium) and records a character and/or a diagram (image) on a surface of the recording medium.
2. Description of the Related Art
An image forming apparatus which records an image (a character and/or a diagram) by jetting a droplet of a liquid (liquid droplet) includes, as in an ink-jet printer, etc., a carriage which reciprocates in a direction of width of a recording medium, and a recording head provided on the carriage and having a plurality of nozzles through which the ink droplets are jetted. Further, during the time when the carriage reciprocates with respect to the recording medium, ink droplets are jetted toward the recording medium from the nozzles in the recording head. Accordingly, an image is formed by ink dots on a surface of the recording medium.
In such an image forming apparatus, a means for realizing a high-speed recording and a high image quality can be exemplified by achieving high image quality by making ink droplets jetted to be minute, and achieving the high-speed recording by increasing a moving (reciprocating) speed of the carriage. However, when an attempt is made to make the ink droplets minute or fine, the diameter of the nozzle becomes small, and by a thickening effect due to the drying of ink inside the nozzles, jetting characteristics are easily to decline at an early stage. On the other hand, when the traveling speed of the carriage is increased, evaporation of a moisture content in the ink advances and thus making the ink dry easily, thereby resulting in thickening of the ink and declining the image quality.
Therefore, as a process for performing the maintenance and recovery of the jetting function by reducing thickening of the ink inside the nozzle, flushing process is carried out. The flushing process includes, for example, a so-called waste jetting (waste discharge) in which thickened ink inside the nozzle is discharged by jetting the ink from the nozzle irrespective of recording (for example, see pages 6 and 7, and FIG. 3 of Japanese Patent Application Laid-open No. 2006-192862).